CVE-2021-40449 Microsoft Windows Win32k Privilege Escalation
A use-after-free flaw in the Windows kernel allows attackers to elevate privileges to SYSTEM level.
- Exploited in the wild
- Since 17 Nov 2021
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-40449?
CVE-2021-40449 is a high-severity use after free vulnerability in Microsoft Windows 10 1507, published on 13 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Win32k Elevation of Privilege Vulnerability
Weakness: CWE-416
Which versions are affected by CVE-2021-40449?
It affects 19 products.
Products include Microsoft Windows 10 1507, Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 1909, Microsoft Windows 10 2004, Microsoft Windows 10 20h2 and 13 more.
How do I fix CVE-2021-40449?
No fix has been published for CVE-2021-40449 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 1 Dec 2021.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2021-40449 being exploited?
Yes. Attackers have exploited CVE-2021-40449 in the wild since at least 17 Nov 2021, including in ransomware campaigns.
Public exploit code: 1 Metasploit module and 7 proofs of concept on GitHub.
Other vulnerabilities in Microsoft Windows 10 1507
- CVE-2017-8543 Microsoft Windows Search Remote Code Execution
- CVE-2025-33053 Microsoft Windows External Control of File Name or Path
- CVE-2025-33073 Microsoft Windows SMB Client Improper Access Control
- CVE-2024-49039 Microsoft Windows Task Scheduler Privilege Escalation
- CVE-2024-43461 Microsoft Windows MSHTML Platform Spoofing
Sources
Also known as GHSA-qjf4-g2gg-w6pq.